Beyond the mosaic model of brain evolution: Rearing environment defines local and global plasticity

Area of Science:

• Neuroscience
• Evolutionary Biology
• Comparative Psychology

Background:

• Comparative animal studies suggest larger brains exhibit more global structural organization, aligning with the concerted model of brain evolution.
• Brain plasticity research indicates environmental factors can independently alter local brain structures, supporting the mosaic model.
• It remains unclear if environmental influences can induce global brain structure changes, questioning the extent of concerted phenotypic plasticity.

Purpose of the Study:

• To investigate the impact of distinct rearing environments on brain organization in the three-spined stickleback (Gasterosteus aculeatus).
• To determine if phenotypic plasticity in brain structure operates in a concerted or mosaic fashion in response to environmental changes.

Main Methods:

• Utilized novel indices to quantify local and global brain structure in sticklebacks.
• Compared brain organization between groups reared in radically different environments.
• Analyzed the predictive relationships between brain structure changes and differences in brain and body sizes.

Main Results:

• Changes in local brain structure significantly predicted variations in both body and brain size.
• Alterations in global brain structure were found to predict only differences in brain size.
• Both local and global brain structure changes were observed, indicating plasticity.

Conclusions:

• Environmental influences can induce both local and global brain structure changes in sticklebacks.
• The observed brain plasticity, encompassing both local and global modifications, is compatible with the concerted model of brain evolution.
• This study demonstrates that brain plasticity can manifest in a concerted manner, affecting overall brain organization in response to environmental stimuli.